Low pH granular detergent composition

Abstract

A high density granular detergent composition having a pH (1% in distilled water) of from about 9.0 to about 10.0, that contains from 5% to about 50% anionic detergent surfactant and from about 3% to about 40% acid pyrophosphate is disclosed. The composition is formed by agglomeration of the acid pyrophosphate and a portion of the surfactant, preferably in a V-blender. The composition contains less than about 1%, but preferably is free of, citric acid.

What is claimed is: 
     
       1. A granular detergent composition having a density of 600 gm/liter or above, and having a pH (1% in distilled water) of from about 9.0 to about 10, comprising by weight: (i) from 13.2% to about 50% detergent anionic surfactant;   (ii) from about 3% to about 40% acid pyrophosphate; and   (iii) less than about 1% of citric acid or salt thereof; and   (iv) less than about 2% of alkali metal silicate;   (v) an inorganic alkaline material wherein said detergent composition is formed by agglomeration of said acid pyrophosphate, said inorganic alkaline material and a portion of said detergent surfactant and there is substantially no alkali metal silicate present during said agglomeration.     
     
     
       2. The granular detergent composition according to claim 1 wherein said composition is essentially free of said citric acid or salt thereof, and substantially free of alkali metal silicates. 
     
     
       3. The granular detergent composition according to claim 1 wherein said composition is made by an agglomeration process wherein at least a portion of said anionic surfactant is formed by dry neutralization of an acid precursor of said portion of said anionic surfactant with an inorganic alkaline material in the presence of said acid pyrophosphate. 
     
     
       4. A process for making the granular detergent composition according to claim 3 comprising the steps of: a) forming a particulate mixture comprising a water-soluble carbonate material and said acid pyrophosphate;   b) mixing and shearing the particulate mixture such that the mixture is partially fluidized; and   c) dispersing the acid precursor into the partially fluidized particulate mixture, thereby neutralizing the acid precursor to form the detergent composition.   
     
     
       5. The process of claim 4 wherein said particulate mixture of step a) comprises a further portion of said anionic surfactant as alkyl sulfate in particulate form. 
     
     
       6. The process of claim 5 wherein said temperature of said mixture of step b) and said detergent composition of step c) is maintained at a temperature no greater than 80° C. 
     
     
       7. The process of claim 6 wherein said steps are conducted in a V-blender equipment.